A forthcoming project requires that a Flash projector (.exe) be kept on a server and accessed by multiple users over network (LAN). There will be a central access database as a back-end. I am using a third party SWF2EXE (SWF Studio) product to have database functionality. I would like to know if sharing an .exe file this way is practical. I know it's not a typical client-server methodology but I can't use Server side platform like ASP due to lack of resources at the client's place. Is it likely to cause any crashes if the same .exe is launched simultaneously by network users doing a simultaneous read/write to database (mdb)?
Each computer should get a copy of the exe file, and it should be only the database which is shared. If you are on a LAN and you are using MS Access, placing the MDB file in a shared location should be fine.
You may also want to check what the concurrent user limit is for an ms access database.
Andrew
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Scenario
I have an application that I have been developing for two years. I use the framework .NET to develop it in a language called Oxygene that comes from Pascal.
When I have something new in my code, I publish my application in File System method. I have a couple servers working on Amazon EC2, so I transfer this files to a folder in my IIS Server. In this IIS Server I already have a website that corresponds to my application, so I just replace the old files for the newest files.
I have another server that works as an SQL server.
Last detail is that in my application the user is able to attach files, import pictures, export PDF and Excel files. Attachments and pictures are stored in the same folder the application is located.
Issue
Here is my problem. I have got a new client that is kind of a big client. It seems like this company has a strong IT security, so the application must be located in their servers.
The big problem is that they required my application to be set in the following architecture:
I am used to only use an app server (works for external access) and a SQL server. They want the third server in DMZ net so they can let external access happen. The reason the application can't be placed in the DMZ is because there are the files I mentioned bellow that the user stores in the application. The database stores all the data, but not those files mentioned.
Solutions I have offered, but won't be accepted:
Publishing the application in a IIS server located in the DMZ: That won't be accepted since my application stores user attachments in the same folder the application is located. There are also images stored there.
Publishing the application in the app server, but also publishing a empty application in the DMZ server redirecting to the IIS server inside the LAN: That's the best solution I have come up.
Using a reverse proxy to protect the LAN Net: This is off the table, since reverse proxy is not safe at all.
I am kind of confused because I can't see a way to separate my application in two to make it work in that suggested architecture.
Can anybody give me a hint or ideas of how this would work?
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You can't "redirect" to inside the LAN, a redirect is a client-side operation, so if the internal server isn't already exposed, you can't redirect someone to it.
A reverse proxy is likely your best bet. Why do you believe it is not safe? This is a tried-and-true solution, it allows you to leave additional ports/services open to internal requests (like a file server, which it sounds like you are trying to expose).
How are these files getting uploaded? Are you using FTP? SMB? HTTP? This solution will not expose those other protocols to the outside world (please don't expose SMB to the outside, it will result in tragedy). Do the external users need to upload these files?
I want to create a desktop application, I normally work on web based applications so have very little knowledge about creating console applications using .Net and visual studio.
So now in this application I'l also be using database connectivity and stored procedures (SQL server). But how should I start doing this as I dont want to install SQL server on my clients system.
thanks in advance..
I think it depends on the goal of your application, the amout and sturcture of the data and the environment. The last point aims to the client system, if the client is part of an enterprise network (e.g. Active Directory) or is a common user at home.
maybe you can use xml or json files to store the data
if you need a database, you can create a setup project for your application which automatically installs a SQL Server express
another way is, if it's applicable for you, your application can consume a webservice which provide the data
you could use SQL Server compact http://msdn.microsoft.com/en-us/library/cc645984(v=sql.100).aspx or SQL Lite to embark your DB in your application without external dependencies.
Otherwise, if offline isn't a requirement, you could go the "cloud" way, with web APIs
I have an existing ASP.NET website that I would like to port to Azure within my free trial.
I would like the migration to be as painless as possible. The application uses log4net and NHibernate, plus it needs to share data with an application supposed to run on a virtual server.
Two questions can be asked as 1
How do I configure paths in Web.config to access a shared drive?
I need to configure the paths into which logs will be stored and, most important, I have to specify where the application will read the files written by the daemon that will run on my Azure Linux VM.
When both the app and the daemon ran on the same server (yes, I had Mono running fine) I just had to choose a shared local directory.
I'm not sure I'm totally understanding the scenario, but I'll try to give you a few options.
One - Windows Azure Web Sites (currently in Preview) could be a great option for your ASP.NET site. Of course, it depends what needs your site has. But, you can write your log4net files with web site and using NHibernate too.
Two - Web roles work great for situations like this. You would likely have to change some code to use blob storage for persistant file storage. You could use Windows Azure drives as a way to get a persistent location for log files. Windows Azure drives don't have a pre-determined drive letter, so you'd want to use the API to get to that. That may, or may not, be a good option for your situation. With web roles you could also write the log4net files to local storage and use Windows Azure diagnostics to transfer them periodically to blob storage. Just another way to persist the files.
Three - Using Windows Azure Virtual Machines (currently in Preview) you could write the log files to a data disk, which is backed by blob storage.
In the end, if you have files you need to share across instances and/or roles, then leveraging blob storage is likely your best option.
I am developing an ASP.NET website. The users can open up the web page and work with data when they are online. But I want to make them able to work when they are offline and submit their changes later when they are online again. The offline application must be very simple to run and I don't want to develop a separate windows application for this purpose.
So I want to build an executable that when starts, first starts up a local IIS and then opens the startup page of my website (which is locally available) in the user's browser.
And of course it would be great if this executable can be installed on the user's system along with my website files, IIS and SQL Server Express all in one package.
OK I re-read your question and see that you will have local IIS and local Database installed on all client systems.
So then the solution is very simple.
The Applicaiton (main form)
Create a windows forms application.
Put a WebBrowser control and a StatusStrip control on the form.
Add two string resources named say LocalStartUrl and OnlineStartUrl, which holds the addresses of your local and online website home/startup pages.
On Form_Load, check for online internet connectivity and accordingly launch either LocalStartUrl or OnlineStartUrl in the webbrowser control. You can show messagebox and use the StatusBar to inform the user of the same.
The sync module:
The database sync module runs in the timer/separate thread and synchronizes your local database with online database in the background. It sends any unsaved changes to the server and downloads any missing data from the server to local database. You would need to control the speed of this module so that user doesn't face difficulty browsing other websites or using the application smoothly etc. It should be slow and steady and send/request only small chunks of data at a time.
When in offline mode, it just periodically checks for online connectivity at regular intervals. As soon as an internet connectivity can be found, the user is informed. If they permit, it switches over to online mode. Otherwise the user continues to work offline until the application is closed and launched again.
In online mode, the sync module syncs data to & from the online database. This doesn't affect the user because they are not connected to this database. Instead they are connected to the online website and database.
It will take efforts to streamline this approach, but ultimately it is achievable easily.
This won't be just a single task. It would be a series of task working together in sync.
Your windows application does the following:
Write the offline changes to a disk file/database etc.
Periodically check the online availability of your website/ftp site.
Whenever the website is found to be available, and there are some cached changes, submit the file to the website/ftp site.
Your server does the following:
Whenever a file is recieved, check for its validity and integrity. If found correct, put it in a specific folder.
A service on your server watches the folder and as soon as any file is found there, processes the file(s)
The service moves the file to another folder (backup) after processing.
I'm trying to access local file system from Flex web application.
I know it is pretty difficult, but I think there must be a way. Is there a way that Flex app can use AIR components or maybe web application can call some AIR module in order to choose files and upload?
There is no direct way that a web based Flex/Flash application can access AIR based APIs. They aren't built into the Flash Player, but are rather extensions built into the AIR runtime. You can't access them directly because they aren't there.
If you have an AIR app installed on the user's local machine you can, in theory, use that app as a proxy with localConnection. That way the AIR app can access the file system directly, triggered by the browser based app. I'm not sure how user interaction would work, though.
If you have server software installed on the client machine, you can trigger file processing commands from Flex using RmoteObject/HTTPService/WebService commands. This wouldn't give the user any interaction ability and is not usually practical unless you have strong control over your client machines.
Either approach would present an app installation nightmare; which almost defeats the purpose of a browser based app in the first place.
You can use FileReference's methods to ask user to select files to open (load into flash, upload into server) or save (from server or bytes from flash).